Escapement noise reducing means



1956 J. L. HANCOCK 3,267,742

ESCAPEMENT NOISE nmnucm MEANS Filed July 6, 1964 INVENTOR. JOHN L. HANCOCK United States Patent 3,267,742 ESCAPEMENT NOISE REDUCING MEANS John L. Hancock, Villa Park, Ill., assignor to Mastercrafters Clock Corporation, Chicago, Ill., a corporation of Illinois Filed July 6, 1964, Ser. No. 380,269 7 Claims. (Cl. 741.5)

This invention relates generally to escapement mechanisms and more particularly to means for reducing the noise which invariably results from the operation of such mechanisms.

Escapement mechanisms are of course many and varied, finding use in clocks, counting devices, typewriters, etc. However, despite their long and widespread use, the great bulk of all escapements are characterized by a common undesirable feature, namely, noisiness of operation. In clocks and the like, this noisiness manifests itself in the well-known ticking or tick-tock noises.

Those skilled in the art will appreciate that the ticking noises of clocks are caused by the continuous striking of the pallet pins by the teeth of the escape wheel. To my knowledge, all prior attempts to silence or mufile escapement noises have involved the resilient or yieldable mounting of the pallet pins as exemplified in Patent No. 2,481,213. Although the prior attempts were partially successful in silencing escapement noise, they were characterized by other disadvantageous features which have resulted in the virtual non-use thereof. The most serious disadvantage of the prior silencing devices was their considerable cost which made their use in popularly priced clocks and watches prohibitive. Moreover, they necessitated the use of specially designed pallet pieces and escape wheels thereby preventing the use of standardized parts.

It is therefore an important object of this invention to provide noise reducing means for escapements which overcomes all of the disadvantages described hereinabove.

Another important object is to afford escapement noise reducing means of the character described employing a novel escape wheel arrangement wherein said wheel is loosely mounted on the escape wheel shaft. A related object is to afford such escapement noise reducing means wherein the escape wheel is itself resiliently or yieldably mounted in relation to the pallet pins.

A further object is to provide escapement noise reducing means of the character described in which the novel escape wheel arrangement affords a flywheel effect which increases the tip velocity of the escape wheel teeth as they leave the impulse face of the pallet pins. A related object is to provide such escapement noise reducing means in which the velocity of the pallet fork and associated balance wheel is increased thereby enhancing the efficiency or time keeping abilities of the clock or other device in which said escapement is employed,

Still another object is to afford escapement noise re ducing means of the character described which may be most inexpensively manufactured of standardized parts to permit use thereof on the cheapest of clock movements, and yet is most eflicient and durable for the purposes intended.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel features of construction, arrange- Patented August 23, 1966 ment and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly-pointed out in the appended claims, it being understood that various changes in the form, proportion, size and minor details of the structure may be made without departing from the spirit or sacrificing any of the advantages of the invention.

For the purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawings a preferred embodiment thereof, from an inspection of which, when considered in connection with the following description, my invention, its mode of construction, assembly and operation, and many of its advantages should be readily understood and appreciated.

Referring to the drawings in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawings:

FIG. 1 is a fragmentary plan view of an escapement mechanism with escapement noise reducing means embodying the principles of the invention;

FIG. 2 is a fragmentary sectional view taken on the plane of line 2-2 in FIG. 1 and viewed in the direction indicated;

FIG. 3 is an exploded plan view illustrating the various parts of the novel escape wheel arrangement; and

FIGS. 4 and 5 are plan views of alternative modified forms of the escape wheel.

Referring more particularly to FIG. 1 of the drawings, it will be seen that the reference numeral 10 indicates generally an escapement mechanism with escapement noise reducing means embodying the principles of the invention. The mechanism 10 comprises a pallet lever or fork 12 which is pivotally mounted on a pin or arbor 14. The fork 12 includes a forked end such as 16 which engages and cooperates with an impulse pin 18 of a balance wheel 20 in the usual manner.

Rigidly connected to the lever 12, and oscillating in unison therewith, is a pallet member 22 having a pair of arms 24, 24. A pallet pin such as 26 is mounted on each of the arms 24 adjacent the free end thereof as indicated, said pin including a locking face 28 and an impulse face 30. The pallet pins 26 are suitably angularly disposed with relation to each other and are adapted to cooperate with the teeth of an escape wheel in a manner well-known to those versed in the art.

Mounted on an escape wheel shaft such as 32 is an escape wheel assembly indicated generally by the numeral 35. As indicated in FIGS. 2 and 3, the escape wheel assembly 35 comprises a central bearing or washer 36 which is mounted on the shaft 32. Loosely mounted on the washer 36 is an escape wheel ring 38 which may comprise an ordinary inexpensive escape wheel from the center of which has been removed the great bulk of its mass. The importance of the removal of mass from the ring 38 will become apparent as the description proceeds. The ring 38 may be provided with a plurality of circumferentially spaced teeth such as 39.

A pair of discs 40, 40 which are of greater diameter than the washer 36, is mounted on shaft 32 to sandwich the washer therebetween. It is important to note that the washer 36 is slightly thicker than the ring 38 so that the discs 40 abut the washer and not the ring. It will thus be appreciated that the ring 38 is capable of rotation upon the washer 36 and between the discs 40. Completing the assembly 35 is a coil spring 42 having one end 44 connected to the shaft 32 and the opposite end 46 positioned over the marginal edges of the discs 40 to thereby connect together as a unit said discs, the ring 38 and the washer 36. Since the spring 42 is under torsion and has a tendency to unwind, the end 46 thereof bears against one of the teeth 39 of the ring 38 to normally urge said ring in the direction of its rotation, or clockwise as indicated by the arrow in FIG. 1.

In operation, the novel escape wheel assembly 35 functions to reduce or eliminate substantially all of the ticking noises produced by prior escapements in which a solid and relatively heavy ordinary escape wheel is rigidly mounted on its shaft. The reasons for this desirable reduction of noise may be described as follows: At the outset, the greatly reduced mass of the ring 38 provides a much lower moment of inertia so that the impact of a tooth 39 striking one of the pins 26 is greatly reduced. The ring 38 is of course yieldably mounted with relation to the pins 26 by means of the spring 42, the torque of said spring normally being just equal to the average torque supplied to the shaft 32 by the gear train associated with the escapement mechanism. Rotation of the ring 38 relative to the discs 40 and in close proximity thereto results in a desirable snubbing or shock absorbing action which tends to dampen sound waves generated by said ring. Moreover, the close proximity of the discs 40 causes said discs to function somewhat as a mute to reduce the amplitude of vibration of any sound waves generated by the ring.

An additional salutary effect of the assembly 35 results from the relatively heavy mass of the discs 40. As will be understood, these discs act as a flywheel to store additional energy in the spring 42. This flywheel effect causes the teeth 39 of the ring 38 to leave the impulse faces 30 of the pins 26 at increased velocity. This in turn results in increased velocity of the balance wheel 20, through the fork 12, thereby helping to maintain better time keeping abilities.

From the foregoing description and drawings, it will be appreciated that I have provided a novel escapement noise reducing means which may be inexpensively manufactured for widespread popular use and yet is most efficient in operation. Even further reduction of noise may be achieved by suitably shock mounting the entire gear train structure incorporating the escapement mechanism in its associated outer housing or casing. Such shock mountings, as by means of rubber grommets, or the like, are of course old and well-known.

Although the assembly 35 has been described as comprising a ring 38, it will be understood that the same may likewise comprise any other suitable escape wheel configuration from which has been removed the bulk of its mass such as, for example, the wheels 38a and 38b illustrated in FIGS, 4 and 5, respectively. In like manner, the pallet pins 26 and the teeth 39 could be reversed to the well-known pin-lever arrangement in which the pallet pins 26 become simple resilient wires, while the teeth 39 change their form to the locking face and impulse face type. It is thus pointed out that any of the well-known escapement mechanisms can be quieted by my invention. Similarly, while the shaft 32 has been illustrated as longitudinally grooved, the same may instead comprise a smooth shaft having a suitable toothed pinion on a portion thereof for connection to the associated gear train.

It is believed that my invention, its mode of con- 4 What I claim and desire to secure by Letters Patent of the United States is:

1. In an escapement mechanism including an escape wheel shaft and an escape wheel mounted on said shaft, means loosely mounting said wheel on said shaft to permit relative rotation therebetween, and means resiliently coupling said wheel to said shaft for rotation therewith, said first-mentioned means comprising a bearing mounted on said shaft, said wheel being rotatably mounted on said hearing, and a pair of members mounted on said shaft and sandwiching said bearing therebetween, the spacing between said members being greater than the thickness of said Wheel whereby said wheel is capable of rotation between said members. 2. The escapement mechanism of claim 1 in which said last-mentioned means comprises a coil spring mounted on said shaft, one end of said spring being connected to said shaft, the opposite end of said spring bearing against said wheel and normally urging said wheel in the direction of rotation of said shaft. 3. An escapement mechanism comprising a narrow annular escape wheel,

an escape wheel shaft, means loosely mounting said wheel on said shaft and permitting relative rotation therebetween, means resiliently coupling said wheel to said shaft for rotation therewith, and a pallet associated with said wheel and engageable thereby, said first-mentioned means, second-mentioned means and escape wheel cooperating to greatly reduce the noise caused by said wheel engaging said pallet, said first-mentioned means comprising a pair of disc-like members mounted on said shaft on opposite sides of said ring, and spacer means spacing said members from said ring whereby said ring is capable of rotation therebetween. 4. The escapement mechanism of claim 3 in which said spacer means comprises an annular bearing mounted on said shaft,

struction and assembly, and many of its advantages should be readily understood from the foregoing without further said bearing being of greater thickness than said ring,

said ring being rotatably mounted on said bearing.

5. The escapement mechanism of claim 4 in which said second-mentioned means comprises a coil spring mounted on said shaft,

one end of said spring being connected to said shaft,

the opposite end of said spring bearing against said ring and normally urging said ring in the direction of rotation of said shaft.

6. A noise reducing escape wheel assembly comprising a shaft,

a low mass escape wheel,

an annular bearing mounted on said shaft,

said wheel being rotatably mounted on said heating,

a pair of discs rigidly mounted on said shaft and sandwiching said bearing therebetween,

and spring means connected between said shaft and wheel and normally urging said wheel in the direction or rotation of said shaft,

said bearing being of greater thickness than said wheel whereby said wheel is capable of rotation between said discs.

7. Esoapement noise reducing means for clocks and the like having a gear train and an outer casing therefor, said means comprising,

a low mass escape wheel having central portions removed therefrom to afford a thin ring,

an escape wheel shaft,

a washer bearing mounted on said shaft and being of slightly greater thickness than said ring,

5 6 said ring being rotatably mounted on said bearing, said ring :and shock absorbing means cooperating to a pair of relatively heavy discs rigidly mounted on said greatly reduce the noise caused by the engagement shaft and abutting opposite sides of said bearing of said ring and pallet, whereby said ring is capable of rotation therebetween, said spring and discs cooperating to provide a flywheel a coil spring mounted on said shaft and having one end 5 efiect to increase the velocity of said pallet as the connected to said shaft and the opposite end bearing same disengages from said ring.

against said ring and the marginal edges of said discs,

said spring normally urging said ring in the direction of References Cited by the Examiner rotation of said shaft, UNITED STATES PATENTS a pallet cooperatively associated with said ring and 10 3,137,122 6/1964 Dinerstein et a1 X engageablethereby, 3,171,244 3/1965 Koplaretal 5s 41 X and resilient shock absorbing means mounting said gear train in said casing, MILTON KAUFMAN, Primary Examiner. 

1. IN AN ESCAPEMENT MECHANISM INCLUDING AN ESCAPE WHEEL SHAFT AND AN ESCAPE WHEEL MOUNTED ON SAID SHAFT, MEANS LOOSELY MOUNTING SAID WHEEL ON SAID SHAFT TO PERMIT RELATIVE ROTATION THEREBETWEEN, AND MEANS RESILIENTLY COUPLING SAID WHEEL TO SAID SHAFT FOR ROTATION THEREWITH, SAID FIRST-MENTIONED MEANS COMPRISING A BEARING MOUNTED ON SAID SHAFT, SAID WHEEL BEING ROTATABLY MOUNTED ON SAID BEARING, AND A PAIR OF MEMBERS MOUNTED ON SAID SHAFT AND SANDWICHING SAID BEARING THEREBETWEEN, THE SPACING BETWEEN SAID MEMBERS BEING GREATER THAN THE THICKNESS OF SAID WHEEL WHEREBY SAID WHEEL IS CAPABLE OF ROTATION BETWEEN SAID MEMBERS. 